Produced fluids coming from an oil well often include a mixture of petroleum, connate water and hydrocarbon gas. In order to prepare the produced fluids for handling, i.e., transportation of the petroleum and gas and disposal of the water, the mixture must be separated into separate components. Since gas in most instances will readily separate from the mixture under conditions prevailing at the surface, the principal problem is separating the produced water from the oil. Water and oil, of course, have different densities and will gravity segregate from each other if left standing long enough. However, this requires a great deal of storage space which can be very undesirable.
Many types of wash tanks have been used heretofore to separate the oil from water. These tanks have used heat, chemicals and baffles to promote separation of the oil and water. The tanks use various arrangements to assist separation of the two fluids so the oil may be withdrawn from the top of the tank and water withdrawn from the bottom of the tank. There is still need, however, for a wash tank which effectively promotes the separation of oil and water so as to permit a relatively small tank to be used, thus saving space and improving the transit time through the tank.